Affinity chromatography is a separation technique based on the reversible, specific interaction of a biological substance in solution or suspension when passed through a subdivided filling holding a complementary biological substance.
Most prior work on affinity chromatography has used a filling comprised of small beads of agarose. Extensive literature exists on means of activating the agarose with suitable chemicals to provide a covalent chemical link for the binding of an antibody so that harvesting of the desired antigenic protein is possible. After the desired antigenic protein has been bound to the filling containing the covalently bonded antibody impurities are washed away and the desired pure antigenic protein is eluted by a solution from which it is easily separated. The eluting solution should leave the filling containing the covalently bonded antibody ready for reuse.
Immobilized enzymes are enzymes suitably held on an extensive surface of the filling and have reached industrial scale use. The support matrix used is often a membrane of suitable shape and porosity. Steric requirements usually dictate that a suitable spacer arm be provided between the support matrix and the covalent chemical link to the enzyme to give high efficiency and selectivity. Suitable spacer arms and the activating chemicals required are described by O. R. Zaborsky in "Immobilised Enzymes", C.R.C. Press, Cleveland, Ohio, 1974.
Canadian Pat. No. 1,083,057 deals with the prior art of forming some suitable porous membranes, their activation and a method of reacting the enzyme whilst forcing it through the membrane.
Although nylons are physically very suitable as a support matrix because of tolerance of sterilising temperatures, stiffness, hydrophilicity and ease of forming, they have been little used since they are difficult to activate, particularly if isothiocyanate end groups are needed.
The reaction of sulphuryl chloride on the polyamide fibre Nylon 6 has been investigated by D. S. Varma and Thomas Eapen. As reported in the Indian Journal of Textile Research, Vol. 1, March 1976, pp. 26-28 their findings were:
"Our results thus indicate that the reaction of Nylon 6 with sulphuryl chloride is accompanied by predominant chain scission reactions. Cross-bond formation is indicated by the appearance of an additional peak in the DTA thermogram. As a result of hydrolysis, a deterioration in the properties is observed." PA1 (i) reacting an aliphatic polyamide with sulphuryl chloride to form an intermediate, and, PA1 (ii) converting the intermediate into the support by providing thereon a covalent chemical link to which the antibodies or enzymes may be bound
These unpromising results confirm the earlier work of S. A. M. El-Garf and Y. Abou-Street in Faserforschung Textiltechnik Vol. 25(6), pp. 248-51, 1974 where it was reported that degradation increased as the temperature increased. Furthermore, the rates of reaction and of degradation were higher in carbon tetrachloride than in toluene.
The Varma and Eapen paper contains no suggestion of useful, reactive intermediates being prepared by the reaction of sulphuryl chloride on Nylon 6.
American Chemical Abstracts record no reactions of sulphuryl chloride with monomeric aliphatic secondary amides, thus giving no expectation of useful intermediates being formed by the reaction of sulphuryl chloride on aliphatic polyamides.